The present invention relates to a lens mount having at least one pair of cylindrical barrels which are slidable relative to each other (as in the barrels of a zoom lens) and a "floating" lens or inner focus lens. More particularly, the invention relates to a means for preventing the generation of sound due to a sliding operation in such a lens mount.
Each of the above-described lens mounts has at least one pair of cylinders which are helicoid coupled and which slide relative to each other while being at least rotated by means of a cam for the purpose of focusing. The sliding cylindrical surfaces of these cylinders should be considerably high in surface accuracy (smoothness) in order to prevent the generation of sound or vibration during the sliding movement. If the surface accuracy is low, then an unacceptably large amount of sound can be generated. Moreover, in such a case, the cylinders tend to wear quickly to the point where the cylinders cannot slide smoothly.
In order to eliminate this difficulty, heretofore, the cylinders, after being machined on a lathe, have been subjected to honing, lapping, buffing or sandpaper finishing so that the surface accuracy thereof is improved, and the cylinders thus treated coated with a dry lubricant to obtain sliding cylindrical surfaces satisfactory in practical use. However, this conventional method is disadvantageous in that the productivity is low, the manufacturing cost is high, and it is difficult to maintain the required dimensional accuracy because it is necessary to provide machining margins for finish dimensions in the machining work and to perform additional surface processing or treating operations.